To man, hand gestures are a natural and intuitive method of communication to interact with the environment. These gestures can serve to emphasize speech, designate or handle objects, or even constitute a language in its own right, like sign language. The information conveyed by hand gestures proves to be much richer than the information that can be supplied using a keyboard or a pointing device such as a mouse. It is thus desirable to use hand gestures to control a device such as a computer.
Therefore, using electronic gloves equipped with sensors supplying the position of the hand and the angles of the finger joints has already been suggested. However, such gloves prove to be relatively cumbersome and costly due to the number of sensors necessary to determine the position of the fingers.
Furthermore, the regular increase in the power of desktop computers and the emergence of cheap video cameras, enable the production of a real-time hand gesture recognition system, suited to desktop computers, to be considered.
Now, the recognition of hand gestures in a sequence of images initially requires locating the contours of the hand in each image in the sequence. For this purpose, certain methods in prior art require the user to wear a colored glove. However, these methods are very sensitive to luminosity variations, to shadows and to changes in background image. In addition, wearing such a glove proves to be unpleasant for the user.
Secondly, hand gesture recognition requires the postural characteristics of the hand located in each image to be determined, and finally hand movements from one image to the next to be followed from the postural characteristics.
The postural characteristics of the hand can be analyzed for example by positioning a skeletal pattern on the hand. However, this technique requires precisely determining the center of the hand. Classically, the center of the hand is determined by calculating the center of gravity of the region delimited by the contours of the hand, from the geometric torque. If the hand also contains the forearm, the center of gravity calculated will be shifted towards the center of the arm.
Furthermore, hand movements are generally followed using a pattern that is difficult to initialize by making hypotheses about the configuration of the hand.